Deployable Doubt Dispellers

nicksanspam · 2006-02-23T16:00:03+00:00

The most popular forms of solar heating seem uneconomical these days, withhigh costs and low solar fractions (20% for some FSEC-certified water heaters),so they seem to require customers who are concerned about climate change,among other things. If solar house heating were to simply cost less thanother forms of house heating, more people might use it...After hearing lots of doubt that low-cost solar house heating can work witha high solar fraction outside of the Southwest from local architects andreporters and others who read SBIC guidelines that say houses in Phila can onlybe 60% solar-heated at best and seeing lots of "solar houses" that are only30-50% solar-heated vs those "with no other form of heat," I think we shoulddispatch Deployable Doubt Dispellers ("D-cubes") to regional Infestations ofDoubt, eg unboltable 8' cubes that stay 70 F for a few cold cloudy days, withlittle windows so people can peer in to see big dial thermometers inside.Lots of people (eg AIA and SBIC and SBSE) seem to have forgotten that thingslike this can be engineered, notwithstanding high-school physics and houses by PE Norman Saunders, who calculates needs for "purchased heat" with Gaussianweather stats in the same way that other engineers calculate 100-year floods: The ASHRAE 1954 Handbook gives the 1% and 2 1/2% temperatures for Boston as 0 and 8 F (-17.8 and -13.4C.) For -15C, the holding time for our houses is three days, giving a standard deviation of 7.8 Kelvin degrees. In December, the 1% temperature is 2.1 standard deviations down... and so can be expected to occur about once every 4.5 years. This suggests the need to purchase heat [or wear a sweater :-] in December once in 35 years.NREL says 1000 Btu/ft^2 of sun falls on a south wall on an average 30 F daywith a 38 F max in Philadelphia. A direct-gain "mass and glass" D-cube (likemost solar houses) with an 8'x8' R4 south window with 50% solar transmissioncould be 80 F on an average day if 0.5x8'x8'x1000 = 24h(80-30)G Btu,...

Feb 23, 2006 23 Replies

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m Ransley 20 years ago

Is that 120 KWH A DAY! I used 180 Kwh last month! Lets see 120 kwh x

125 x 30 days equals a monthly electric bill of 450$$. So your " solar" house is electricly heated! But of course it was a Typo, or im just reading it wrong.

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m Ransley 20 years ago

Line 17 of 3460 " EGAIN=226/27` indoor electrical use (kwh/day) 120. " If 120 isnt kwh what is it.

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nicksanspam 20 years ago

m Ransley errs again:

No.

Nick

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m Ransley 20 years ago

You forgot 30 pages

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